This section provides background information related to the present disclosure which is not necessarily prior art.
With a magnetorheological clutch, the degree of coupling between a primary part of the clutch and a secondary part of the clutch is controlled by a magnetic field (magnetic induction). The parameter regulating the coupling in this respect is the viscosity of a magnetorheological medium that is arranged between the primary part and the secondary part of the clutch, with the viscosity being dependent on the magnetic field. The magnetorheological medium may, for example, be a magnetorheological powder, gel, or fluid.
Magnetorheological multi-disk clutches are generally known whose primary part and secondary part are rotationally fixedly connected to disks. The disks connected to the primary part are arranged alternately with the disks connected to the secondary part. The gaps between the disks are filled with a magnetorheological medium, which has a viscosity that increases as the magnetic field strength increases. If the gaps are acted on by a magnetic field, the viscosity of the magnetorheological medium increases and a mechanical coupling is established between the disks of the primary part and the disks of the secondary part due to the increasing friction, whereby a torque transfer may take place from the primary part to the secondary part—or vice versa.
However, the disks—provided they are made of magnetizable material—have an effect that shields the magnetic field. To minimize the effect of the shielding and to provide a sufficiently strong magnetic field for the effective magnetization of the magnetorheological fluid in the plurality of coupling gaps disposed sequentially in the direction of the magnetic field, the disks are usually provided with openings (e.g. open slots or slots provided with plastic inserts). In other words, the disks have zones of smaller magnetic permeability to reduce the magnetic shield effect of the disks.
By this measure, the coupling gaps are acted on by a sufficiently strong magnetic field to cause the desired changes in viscosity of the magnetorheological fluid. However, the openings reduce the mechanical stability of the disks and, therefore, the load capability of the clutch. In addition, the establishing of the openings requires an additional production step, which has a negative effect on the manufacturing costs of the known clutches.